I'm trying this acyclovir cream which is an antiviral cream too
I have an amoeba infection. I've been swabbing the nose with qtips H202, peroxide which doesn't seem bad if you rinse the area after.
This is an article that would have been helpful for your father.
http://www.endfatigue.com/health_articles_r-s/Sinusitis-actually_a_yeast_infection.html
I suspect your nose has a little touch of a fungal infection like ringworm or candida. I have used Lotrimin cream in my nose when I've had issues like that. It worked well BUT made my nose run heavily while I used it. Like you would need to have a good supply of tissues with you and/or do it when you were at home. a lot. You'd probably need to treat it for a week at least. Get the regular formula, not Ultra because the Ultra one has caused little skin cysts for me.. It doesn't matter if you get the one that says it's for athlete's foot or jock itch - it's all the same medicine for a fungus, but do stick with the cream, not a spray for this.